Acoustic attenuation panel comprising at least one c-shaped reinforcement held by at least one expandable core and method for manufacturing such a panel

Abstract

An acoustic attenuation panel with at least one acoustically resistive layer, at least one reflective layer, at least one cellular structure and at least one C-shaped reinforcement which are interposed between the acoustically resistive and reflective layers, and at least one expandable core, positioned between the first and second wings of the C-shaped reinforcement, which increases in volume during a polymerization cycle. Also a method for manufacturing such a panel.

Claimed is: 
     
         1 . An acoustic attenuation panel comprising:
 at least one acoustically resistive layer;   at least one reflective layer;   at least one cellular structure; and   at least one C-shaped reinforcement interposed between the at least one acoustically resistive layer and the at least one reflective layer,   said at least one C-shaped reinforcement comprising
 a web and a first wing and a second wing in contact respectively with the at least one acoustically resistive layer and the at least one reflective layer, 
   wherein the acoustic attenuation panel further comprises at least one expandable core positioned between the first wing and the second wing of the at least one C-shaped reinforcement and configured to occupy a non-expanded first state, at a first temperature, in which the at least one expandable core occupies a first volume, and an expanded second state, at a second temperature greater than the first temperature, in which the at least one expandable core occupies a second volume greater than the first volume.   
     
     
         2 . The acoustic attenuation panel as claimed in  claim 1 , wherein the at least one expandable core comprises, in the first state, shapes which conform to those of the web and that of the first wing and the second wing of the at least one C-shaped reinforcement. 
     
     
         3 . The acoustic attenuation panel as claimed in  claim 2 , wherein the at least one expandable core comprises, in the first state, a substantially rectangular section which has a length substantially equal to a spacing between the first wing and the second wing and a width substantially equal to that of the first wing and the second wing. 
     
     
         4 . The acoustic attenuation panel as claimed in  claim 1 , wherein the at least one acoustic attenuation panel comprises a plurality of expandable cores placed end to end. 
     
     
         5 . The acoustic attenuation panel as claimed in  claim 1 , wherein the at least one expandable core is produced from a solid material. 
     
     
         6 . The acoustic attenuation panel as claimed in  claim 1 , wherein the at least one expandable core comprises at least one bladder containing an expandable fluid. 
     
     
         7 . The acoustic attenuation panel as claimed in  claim 1 , wherein at least one expandable core is permanently positioned in the acoustic attenuation panel. 
     
     
         8 . The acoustic attenuation panel as claimed in  claim 1 , wherein the first temperature is equal to an ambient temperature and the second temperature is equal to a polymerization temperature greater than or equal to 100° C. 
     
     
         9 . A method for manufacturing an acoustic attenuation panel, the manufacturing method comprising:
 providing at least one acoustically resistive layer, at least one C-shaped reinforcement, at least one cellular structure, and at least one reflective layer, the at least one cellular structure and the at least one C-shaped reinforcement being interposed between the at least one acoustically resistive layer and the at least one reflective layer, said at least one C-shaped reinforcement comprising a web and a first wing and a second wing in contact respectively with the at least one acoustically resistive layer and the at least one reflective layer;   providing at least one polymerization tool;   performing a polymerization cycle; and demolding an acoustic attenuation panel from the at least one polymerization tool;   wherein the method further comprises introducing at least one expandable core between the first wing and the second wing of the C-shaped reinforcement prior to the polymerization cycle, said at least one expandable core being configured to occupy a non-expanded first state, at a first temperature, in which the at least one expandable core occupies a first volume, and an expanded second state, at a second temperature greater than the first temperature, in which the at least one expandable core occupies a second volume greater than the first volume.